Resonant conversion control method and device with a very low standby power consumption

Abstract

A resonant conversion control device with a very low standby power consumption has an AC-to-DC conversion unit, a DC-to-DC conversion unit, a DC-to-DC conversion control unit, and a standby mode control unit. The resonant conversion control device effectively makes use of the low switching loss characteristic of a resonant conversion device, and uses the output voltage for judgement of the system operation mode. The resonant conversion control device can control the action statuses of the AC-to-DC conversion unit and the DC-to-DC conversion unit to lower effectively the power consumption under the standby mode. Therefore, the resonant conversion control device can solve the problem of a higher standby power consumption of conventional switching power supplies and meet the requirements of future standby power standards.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the invention [0002] The present invention relates to a conversion control method and device with a very low standby power consumption and, more particularly, to a conversion control method and device capable of achieving a higher conversion efficiency and a very low standby power consumption under any load conditions. [0003] 2. Description of Related Art [0004] Owing to gradual exhaustion of usable energy, the exploitation of various kinds of energies and restriction of energy use are now becoming a common consensus worldwide. Well-developed countries like the US, Europe, and Japan have made appropriate energy policies for energy use. The standards of power consumption in the standby mode (i.e., green power) of electrical products are generally set below 0.5-1 watt to avoid excessive power consumption when electrical products are standing by. Manufacturers of relevant electronic products have developed appropriate products (power-savin...

AI Technical Summary

Benefits of technology

[0009] An object of the present invention is to provide a resonant conversion control method and device with a very low standby power consumption to enhance the conversion efficiency and solve the standby power consumption problem of conventional switching power supplies.

[0010] To achieve the above object, the present invention adjusts the switching frequency according to the frequency response and load condition of resonant components in a resonant conversion device to regulate and stabilize the output voltage, and makes use of the energy conversion characteristic of the resonant conversion device to accomplish easily zero-voltage switching, hence achieving a higher converter efficiency. Under the condition of a large load current output specification, a synchronous rectifying circuit is adopted to enhance the whole conversion efficiency. Moreover, a hysteresis comparison control is adopted to control the actions of the resonant conversion device at the appropriate time (generally under a very light load or no load), thereby achieving a very low power consumption in the standby mode.

[0012] The DC-to-DC conversion unit is used to convert the first DC voltage to a required second DC voltage. The DC-to-DC conversion unit adjusts the switching frequency to regulate and stabilize the second DC voltage based on the load situation. A diode or a synchronous rectifying circuit can be used as the output rectifier of the DC-to-DC conversion unit. The DC-to-DC conversion control unit receives a feedback signal of the output voltage of the DC-to-DC conversion unit to adjust the frequency of a control signal of a power transistor of the DC-to-DC conversion unit, thereby stabilizing the system output voltage. The DC-to-DC conversion control unit can also provide a control signal for a synchronous rectifying power transistor when a synchronous rectifying circuit is used in the DC-to-DC conversion unit.

[0020] The resonant conversion control method and device with a very low standby power consumption of the present invention can effectively reduce the switching power loss under normal operation. Moreover, the action statuses of the PFC and the DC-to-DC conversion unit can be controlled under different load and voltage conditions, hence effectively lowering the standby power consumption. Furthermore, as compared with the prior art, it is not necessary to use an extra snubber. Under a light load and no load condition, because the system operates at high frequencies, the core power loss is much smaller than that in the prior art. The system power consumption in the standby mode can thus be reduced.

Problems solved by technology

Power consumption also accompanies use of the snubber.

Moreover, a common flyback converter cannot accomplish soft-switching without using special control or auxiliary switches.

Power consumption also accompanies hard-switching of the power transistor.

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